Plastic film has long been made by inflating a tubular section being extruded from an annular orifice in a die to define a tubular film bubble and then collapsing the tube between a pair of cooperating rollers to define a double thickness film which is rolled on a take-up roll. Control of the temperature of a plastic melt flowing through an extrusion die has been a problem. Degradation of the melt within the die or build-up of solidified melt along the inner lip of the die outlet can have adverse effects on film quality and shorten the operating cycle of the die before the die must be shut down for recleaning of the die passages. Temperature control is important for achieving uniform gauge across the width of the film strip after slitting of the extruded tube. Any lack of uniform gauge is magnified when the film is subsequently stretched, as it frequently is for purposes of making oriented heat-shrinkable film.